Laser Harp – Schematic

The fundamental principle behind the laser harp is that a laser shines on a photoresistor making the resistance in the photoresistor close to 0 ohm, and when the a finger is blocking the laser from making contact with the photoresistor, the resistance goes to almost 200k ohm. By using the photoresistors as pulldown resistors in parallel with another set of resistors, the voltage divider rule can be applied to determine what the voltage values will be when the laser is broken. High and low voltages can be sent to the Atmega328p to determine when to play a note.

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